CAMBRIDGE, MASS.
— When classes adjourn here at the Fayerweather Street School, eighth-graders ignore the mall down the street and go straight to the place they consider much cooler: the local natural-foods grocer.

There they gather in groups of 10 or more sometimes, smitten by a marketing atmosphere that links attractiveness to eating well. And when time comes to buy something even as small as a chocolate treat, they feel good knowing a farmer somewhere probably received a good price.

"Food is something you need to stay alive," says eighth-grader Emma Lewis. "Paying farmers well is really important because if we didn't have any [unprocessed] food, we'd all be living on Twinkies."

Eating morally, as some describe it, is becoming a priority for teenagers as well as adults in their early 20s. What began a decade ago as a concern on college campuses to shun clothing made in overseas sweatshops has given birth to a parallel phenomenon in the food and beverage industries. Here, youthful shoppers are leveraging their dollars in a bid to reduce pesticide usage, limit deforestation, and make sure farmers aren't left with a pittance on payday.

Once again, college campuses are setting the pace. Students at 30 colleges have helped persuade administrators to make sure all cafeteria coffee comes with a "Fair Trade" label, which means bean pickers in Latin America and Africa were paid higher than the going rates. Their peers on another 300 campuses are pushing to follow suit, according to Students United for Fair Trade in Washington, D.C.

Coffee is just the beginning. Bon Appétit, an institutional food-service provider based in Palo Alto, Calif., relies on organic and locally grown produce. In each year since 2001, more than 25 colleges have asked the company to bid on their food-service contracts. Though Bon Appétit intentionally limits its growth, its collegiate client list has grown from 58 to 71 in that period.

"It's really just been in the last five years that we've seen students become concerned with where their food was coming from," says Maisie Ganzler, Bon Appétit's director of strategic initiatives. "Prior to that, students were excited to be getting sugared cereal."

To reach a younger set that often doesn't drink coffee, Fair Trade importer Equal Exchange rolled out a line of cocoa in 2003 and chocolate bars in 2004. Profits in both sectors have justified the project, says Equal Exchange co-president Rob Everts. What's more, dozens of schools have contacted the firm to use its products in fundraisers and as classroom teaching tools.

"Kids often are the ones who agitate in the family" for recycling and other eco-friendly practices, Mr. Everts says. "So it's a ripe audience."

Concerns of today's youthful food shoppers seem to reflect in some ways the idealism that inspired prior generations to join boycotts in solidarity with farm workers. But today's efforts are distinct in that youthful consumers say they don't want to make sacrifices. They want high-quality, competitively priced goods that don't require exploitation of workers or the environment. They'll gladly reward companies that deliver.

One activist who shares this sentiment and hears it repeatedly from her peers is Summer Rayne Oakes, a recent college graduate and fashion model who promotes stylish Fair Trade clothing.

"I'm not going to buy something that can't stand on its own or looks bad just because it's socially responsible," Ms. Oakes says. "My generation has come to terms with the fact that we're all consumers, and we all buy something.... So if I do have to buy [food], what are the consequences? Who am I affecting on the planet? What am I affecting on the planet?"

Wanting to ameliorate the world's big problems can be frustrating, especially for those who feel ineffective because they're young. Marketers are figuring out that teenagers resent this feeling of powerlessness and are pushing products that make young buyers feel as though they're making a difference, says Michael Wood, vice president of Teenage Research Unlimited, a market-research firm in Northbrook, Ill. His example: Ethos Water from Starbucks, which contributes five cents from every bottle sold to water-purification centers in developing countries.

"This is a very easy way for young people to contribute.... All they have to do is buy a bottled water," Mr. Wood says. "Buying products or supporting companies that give them ways to support global issues is one way for them to get involved, and they really appreciate that."

Convenience is also driving consumer activism. Joe Curnow, national coordinator of United Students for Fair Trade, says she first got involved about five years ago as a high schooler when she spent time hanging out in cafes. Buying coffee with an eco-friendly label "was a very easy way for me to express what I believed in," she says.

For young teens, consumption is their first foray into activism. At the Fayerweather Street School, Emma Lewis teamed up with classmates Kayla Kleinman and Therese LaRue to sell Fair Trade chocolate, cocoa, and other products at a school fundraiser in November. When the tally reached $8,000, they realized they were striking a chord.

"It's maybe not making as much of a difference as it would if we were adults," Kayla says. "But it is doing something."

Some adults hasten to point out the limitations of ethical consumption as a tool for doing good deeds and personal growth. Gary Lindsay, director of Children's Ministries at Grace Baptist Church in Hudson, Mass., encourages Fair Trade purchases, but he also organizes children to collect toys for foster children and save coins for a playground-construction project in Tanzania. He says it helps them learn to enjoy helping others even when they're not getting anything tangible in return.

"When we're benefiting, how much are we really giving? Is it really sacrifice?" Mr. Lindsay asks. Of Fair Trade products, he says: "Those things are great when we're given opportunities like that once in a while. But I think for us to expect that we should get something out of everything we do is a very selfish attitude to have."

Others say that the Millennial generation was destined to bring their concerns to bear on food products as a result of the way they grew up. And justice in the fields isn't always the foremost concern.

Through child safety seats and other protective products, "this generation has been made to feel so special and so important that they are very concerned with themselves and what goes into their bodies," Bon Appétit's Ms. Ganzler says. "They believe, 'I'm unique, and I deserve to have food that is good for me.' ... I'd venture to guess [concerns about farm workers are] lower on the priority list than what actually impacts themselves."

Although Equal Exchange prices its products competitively with other premium brands, the ethical consumption trend is most visible among the financially comfortable. Bon Appétit doesn't serve public college campuses, she says, because they don't provide enough latitude for the firm's teaching mission. Even on private campuses, many students don't seem motivated to advance a cause.

"The number of students who care about these issues is certainly growing, but it does remain a vocal minority," Ganzler says. "It is not the majority of students that are engaged in related issues.... Most students are going about their business worrying about finals."

Apathy and finances aside, image still matters in junior high and beyond. And in some circles, food is a big part of it.

"If I were to come into school with a Coke, I wouldn't feel as cool as if I came in with a mango-tango smoothie," Emma says. "Looking healthy and being healthy makes you, like, feel good and feel like you look good."